Looks like 4 or 5 people involved there.
Its safe to assume you didn't do those photoshop buttplug images
Its tough because of the retro styling.
But I'll guess you did the big painted style superman on the right with the highlights.
Also the other two in the sequence maybe.
Looks like a rush job though.

I can't really say. It's probably not one of those who have the arms drawn in two separate segments, since in all of Mike's artwork I've seen he's drawn the arms in only one part like it looks in real life.